refactor(gpu): Integrate WebGPU via system wgpu-native and glfw3webgpu

Replaces the complex wgpu-native submodule and manual platform-specific surface creation with a system-wide wgpu-native install (via Homebrew) and the glfw3webgpu helper library.

- Updates scripts/project_init.sh to fetch glfw3webgpu and ensure wgpu-native is installed.

- Refactors CMakeLists.txt to link against the system wgpu-native library.

- Simplifies src/platform.cc to use glfwCreateWindowWGPUSurface.

- Simplifies src/gpu/gpu.cc to use standard WebGPU headers.

- Updates FETCH_DEPS.md with new installation instructions.

- Updates PROJECT_CONTEXT.md with the new integration strategy.

2 files changed, 243 insertions, 0 deletions

diff --git a/third_party/glfw3webgpu/glfw3webgpu.c b/third_party/glfw3webgpu/glfw3webgpu.c
new file mode 100644
index 0000000..27bf9ec
--- /dev/null
+++ b/third_party/glfw3webgpu/glfw3webgpu.c
@@ -0,0 +1,181 @@
+/**
+ * This is an extension of GLFW for WebGPU, abstracting away the details of
+ * OS-specific operations.
+ * 
+ * This file is part of the "Learn WebGPU for C++" book.
+ *   https://eliemichel.github.io/LearnWebGPU
+ * 
+ * Most of this code comes from the wgpu-native triangle example:
+ *   https://github.com/gfx-rs/wgpu-native/blob/master/examples/triangle/main.c
+ * 
+ * MIT License
+ * Copyright (c) 2022-2025 Elie Michel and the wgpu-native authors
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "glfw3webgpu.h"
+
+#include <webgpu.h>
+
+#include <GLFW/glfw3.h>
+
+#ifdef __EMSCRIPTEN__
+#  define GLFW_EXPOSE_NATIVE_EMSCRIPTEN
+#  ifndef GLFW_PLATFORM_EMSCRIPTEN // not defined in older versions of emscripten
+#    define GLFW_PLATFORM_EMSCRIPTEN 0
+#  endif
+#else // __EMSCRIPTEN__
+#  ifdef _GLFW_X11
+#    define GLFW_EXPOSE_NATIVE_X11
+#  endif
+#  ifdef _GLFW_WAYLAND
+#    define GLFW_EXPOSE_NATIVE_WAYLAND
+#  endif
+#  ifdef _GLFW_COCOA
+#    define GLFW_EXPOSE_NATIVE_COCOA
+#  endif
+#  ifdef _GLFW_WIN32
+#    define GLFW_EXPOSE_NATIVE_WIN32
+#  endif
+#endif // __EMSCRIPTEN__
+
+#ifdef GLFW_EXPOSE_NATIVE_COCOA
+#  include <Foundation/Foundation.h>
+#  include <QuartzCore/CAMetalLayer.h>
+#endif
+
+#ifndef __EMSCRIPTEN__
+#  include <GLFW/glfw3native.h>
+#endif
+
+WGPUSurface glfwCreateWindowWGPUSurface(WGPUInstance instance, GLFWwindow* window) {
+#ifndef __EMSCRIPTEN__
+    switch (glfwGetPlatform()) {
+#else
+    // glfwGetPlatform is not available in older versions of emscripten
+    switch (GLFW_PLATFORM_EMSCRIPTEN) {
+#endif
+
+#ifdef GLFW_EXPOSE_NATIVE_X11
+    case GLFW_PLATFORM_X11: {
+        Display* x11_display = glfwGetX11Display();
+        Window x11_window = glfwGetX11Window(window);
+
+        WGPUSurfaceSourceXlibWindow fromXlibWindow;
+        fromXlibWindow.chain.sType = WGPUSType_SurfaceSourceXlibWindow;
+        fromXlibWindow.chain.next = NULL;
+        fromXlibWindow.display = x11_display;
+        fromXlibWindow.window = x11_window;
+
+        WGPUSurfaceDescriptor surfaceDescriptor;
+        surfaceDescriptor.nextInChain = &fromXlibWindow.chain;
+        surfaceDescriptor.label = (WGPUStringView){ NULL, WGPU_STRLEN };
+
+        return wgpuInstanceCreateSurface(instance, &surfaceDescriptor);
+    }
+#endif // GLFW_EXPOSE_NATIVE_X11
+
+#ifdef GLFW_EXPOSE_NATIVE_WAYLAND
+    case GLFW_PLATFORM_WAYLAND: {
+        struct wl_display* wayland_display = glfwGetWaylandDisplay();
+        struct wl_surface* wayland_surface = glfwGetWaylandWindow(window);
+
+        WGPUSurfaceSourceWaylandSurface fromWaylandSurface;
+        fromWaylandSurface.chain.sType = WGPUSType_SurfaceSourceWaylandSurface;
+        fromWaylandSurface.chain.next = NULL;
+        fromWaylandSurface.display = wayland_display;
+        fromWaylandSurface.surface = wayland_surface;
+
+        WGPUSurfaceDescriptor surfaceDescriptor;
+        surfaceDescriptor.nextInChain = &fromWaylandSurface.chain;
+        surfaceDescriptor.label = (WGPUStringView){ NULL, WGPU_STRLEN };
+
+        return wgpuInstanceCreateSurface(instance, &surfaceDescriptor);
+    }
+#endif // GLFW_EXPOSE_NATIVE_WAYLAND
+
+#ifdef GLFW_EXPOSE_NATIVE_COCOA
+    case GLFW_PLATFORM_COCOA: {
+        id metal_layer = [CAMetalLayer layer];
+        NSWindow* ns_window = glfwGetCocoaWindow(window);
+        [ns_window.contentView setWantsLayer : YES] ;
+        [ns_window.contentView setLayer : metal_layer] ;
+
+        WGPUSurfaceSourceMetalLayer fromMetalLayer;
+        fromMetalLayer.chain.sType = WGPUSType_SurfaceSourceMetalLayer;
+        fromMetalLayer.chain.next = NULL;
+        fromMetalLayer.layer = metal_layer;
+
+        WGPUSurfaceDescriptor surfaceDescriptor;
+        surfaceDescriptor.nextInChain = &fromMetalLayer.chain;
+        surfaceDescriptor.label = (WGPUStringView){ NULL, WGPU_STRLEN };
+
+        return wgpuInstanceCreateSurface(instance, &surfaceDescriptor);
+    }
+#endif // GLFW_EXPOSE_NATIVE_COCOA
+
+#ifdef GLFW_EXPOSE_NATIVE_WIN32
+    case GLFW_PLATFORM_WIN32: {
+        HWND hwnd = glfwGetWin32Window(window);
+        HINSTANCE hinstance = GetModuleHandle(NULL);
+
+        WGPUSurfaceSourceWindowsHWND fromWindowsHWND;
+        fromWindowsHWND.chain.sType = WGPUSType_SurfaceSourceWindowsHWND;
+        fromWindowsHWND.chain.next = NULL;
+        fromWindowsHWND.hinstance = hinstance;
+        fromWindowsHWND.hwnd = hwnd;
+
+        WGPUSurfaceDescriptor surfaceDescriptor;
+        surfaceDescriptor.nextInChain = &fromWindowsHWND.chain;
+        surfaceDescriptor.label = (WGPUStringView){ NULL, WGPU_STRLEN };
+
+        return wgpuInstanceCreateSurface(instance, &surfaceDescriptor);
+    }
+#endif // GLFW_EXPOSE_NATIVE_WIN32
+
+#ifdef GLFW_EXPOSE_NATIVE_EMSCRIPTEN
+    case GLFW_PLATFORM_EMSCRIPTEN: {
+#  ifdef WEBGPU_BACKEND_EMDAWNWEBGPU
+        WGPUEmscriptenSurfaceSourceCanvasHTMLSelector fromCanvasHTMLSelector;
+        fromCanvasHTMLSelector.chain.sType = WGPUSType_EmscriptenSurfaceSourceCanvasHTMLSelector;
+        fromCanvasHTMLSelector.selector = (WGPUStringView){ "canvas", WGPU_STRLEN };
+#  else
+        WGPUSurfaceDescriptorFromCanvasHTMLSelector fromCanvasHTMLSelector;
+        fromCanvasHTMLSelector.chain.sType = WGPUSType_SurfaceDescriptorFromCanvasHTMLSelector;
+        fromCanvasHTMLSelector.selector = "canvas";
+#  endif
+        fromCanvasHTMLSelector.chain.next = NULL;
+
+        WGPUSurfaceDescriptor surfaceDescriptor;
+        surfaceDescriptor.nextInChain = &fromCanvasHTMLSelector.chain;
+#  ifdef WEBGPU_BACKEND_EMDAWNWEBGPU
+        surfaceDescriptor.label = (WGPUStringView){ NULL, WGPU_STRLEN };
+#  else
+        surfaceDescriptor.label = NULL;
+#  endif
+        return wgpuInstanceCreateSurface(instance, &surfaceDescriptor);
+    }
+#endif // GLFW_EXPOSE_NATIVE_EMSCRIPTEN
+
+    default:
+        // Unsupported platform
+        return NULL;
+    }
+}
diff --git a/third_party/glfw3webgpu/glfw3webgpu.h b/third_party/glfw3webgpu/glfw3webgpu.h
new file mode 100644
index 0000000..729afcc
--- /dev/null
+++ b/third_party/glfw3webgpu/glfw3webgpu.h
@@ -0,0 +1,62 @@
+/**
+ * This is an extension of GLFW for WebGPU, abstracting away the details of
+ * OS-specific operations.
+ * 
+ * This file is part of the "Learn WebGPU for C++" book.
+ *   https://eliemichel.github.io/LearnWebGPU
+ * 
+ * MIT License
+ * Copyright (c) 2022-2024 Elie Michel and the wgpu-native authors
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef _glfw3_webgpu_h_
+#define _glfw3_webgpu_h_
+
+#include <webgpu.h>
+#include <GLFW/glfw3.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*! @brief Creates a WebGPU surface for the specified window.
+ *
+ *  This function creates a WGPUSurface object for the specified window.
+ *
+ *  If the surface cannot be created, this function returns `NULL`.
+ *
+ *  It is the responsibility of the caller to destroy the window surface. The
+ *  window surface must be destroyed using `wgpuSurfaceRelease`.
+ *
+ *  @param[in] instance The WebGPU instance to create the surface in.
+ *  @param[in] window The window to create the surface for.
+ *  @return The handle of the surface.  This is set to `NULL` if an error
+ *  occurred.
+ *
+ *  @ingroup webgpu
+ */
+WGPUSurface glfwCreateWindowWGPUSurface(WGPUInstance instance, GLFWwindow* window);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // _glfw3_webgpu_h_